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Superfund Innovative Technology Evaluation: Demonstration Bulletin: Organic Extraction Utilizing Solvents
Citation:
U.S. EPA. Superfund Innovative Technology Evaluation: Demonstration Bulletin: Organic Extraction Utilizing Solvents. U.S. Environmental Protection Agency, Washington, DC, EPA/540/M5-89/006, 1989.
Impact/Purpose:
to infom the public
Description:
This technology utilizes liquified gases as the extracting solvent to remove organics, such as hydrocarbons, oil and grease, from wastewater or contaminated sludges and soils. Carbon dioxide is generally used for aqueous solutions, and propane is used for sediment, sludges and soils (semisolids). Contaminated sediments are fed into the top of the extractor (Figure 1). Solvent (condensed by compression at 70 °F) flows upwards through the extractor, making non-reactive contact with the waste. Typically, 99 percent of the organics are dissolved out by the solvent. Then, clean material is removed from the extractor. A mixture of solvent and organics leave the extractor, passing to the separator through a valve where pressure is partially reduced. In the separator, the solvent is vaporized and recycled as fresh solvent. Finally, the organics are drawn off from the separator, recovered for disposal, or reused off-site in industrial processes. The difference in the mobile units for aqueous solutions and semisolids can be found in the extractor. For example, mixing variations can exist in the extractor whereby aqueous solutions can go through one type of mixer having a series of trays while semisolids can go through a "cement-type" mixer.